Molecular cyclo-P3 complexes of the rare-earth elements via a one-pot reaction and selective reduction.

Synthesis of new organo-lanthanide polyphosphides with an aromatic cyclo-[P4]2- moiety and a cyclo-[P3]3- moiety is presented. For this purpose, the divalent LnII-complexes [(NON)LnII(thf)2] (Ln = Sm, Yb) ((NON)2- = 4,5-bis(2,6-diisopropylphenyl-amino)-2,7-di-tert-butyl-9,9-dimethylxanthene) and trivalent LnIII-complexes [(NON)LnIIIBH4(thf)2] (Ln = Y, Sm, Dy) were used as precursors in the reduction process of white phosphorus. While using [(NON)LnII(thf)2] as a one-electron reducing agent the formation of organo-lanthanide polyphosphides with a cyclo-[P4]2- Zintl anion was observed. For comparison, we investigated a multi-electron reduction of P4 by a one-pot reaction of [(NON)LnIIIBH4(thf)2] with elemental potassium. As products molecular polyphosphides with a cyclo-[P3]3- moiety were isolated. The same compound could also be obtained by reducing the cyclo-[P4]2- Zintl anion within the coordination sphere of SmIII in [{(NON)SmIII(thf)2}2(µ-η4:η4-P4)]. Reduction of a polyphosphide within the coordination sphere of a lanthanide complex is unprecedented. Additionally, the magnetic properties of the dinuclear DyIII-compound bearing a bridging cyclo-[P3]3- moiety were investigated.

A Structural Diversity of Molecular Alkaline-Earth-Metal Polyphosphides: From Supramolecular Wheel to Zintl Ion.

A series of molecular group 2 polyphosphides has been synthesized by using air-stable [Cp*Fe(η5 -P5 )] (Cp*=C5 Me5 ) or white phosphorus as polyphosphorus precursors. Different types of group 2 reagents such as organo-magnesium, mono-valent magnesium, and molecular calcium hydride complexes have been investigated to activate these polyphosphorus sources. The organo-magnesium complex [(Dipp BDI-Mg(CH3 ))2 ] (Dipp BDI={[2,6-i Pr2 C6 H3 NCMe]2 CH}- ) reacts with [Cp*Fe(η5 -P5 )] to give an unprecedented Mg/Fe-supramolecular wheel. Kinetically controlled activation of [Cp*Fe(η5 -P5 )] by different mono-valent magnesium complexes allowed the isolation of Mg-coordinated formally mono- and di-reduced products of [Cp*Fe(η5 -P5 )]. To obtain the first examples of molecular calcium-polyphosphides, a molecular calcium hydride complex was used to reduce the aromatic cyclo-P5 ring of [Cp*Fe(η5 -P5 )]. The Ca-Fe-polyphosphide is also characterized by quantum chemical calculations and compared with the corresponding Mg complex. Moreover, a calcium coordinated Zintl ion (P7 )3- was obtained by molecular calcium hydride mediated P4 reduction.